The invention relates to computer speech recognition, particularly to the recognition of spoken computer commands. When a spoken command is recognized, the computer performs one or more functions associated with the command.
In general, a speech recognition apparatus consists of an acoustic processor and a stores set of acoustic models. The acoustic processor measures sound features of an utterance. Each acoustic model represents the acoustic features of an utterance of one or more words associated with the model. The sound features of the utterance are compared to each acoustic model to produce a match score. The match score for an utterance and an acoustic model is an estimate of the closeness of the sound features of the utterance to the acoustic model.
The word or words associated with the acoustic model having the best match score may be selected as the recognition result. Alternatively, the acoustic match score may be combined with other match scores, such as additional acoustic match scores and language model match scores. The word or words associated with the acoustic model or models having the best combined match score may be selected as the recognition result.
For command and control applications, the speech recognition apparatus preferably recognizes an uttered command, and the computer system then immediately executes the command to perform a function associated with the recognized command. For this purpose, the command associated with the acoustic model having the best match score may be selected as the recognition result.
A serious problem with such systems, however, is that inadvertent sounds such as coughs, sighs, or spoken words not intended for recognition can be misrecognized as valid commands. The computer system then immediately executes the misrecognized commands to perform the associated functions with unintended consequences.